2021-04-25 18:27 GMT+02:00, Larry Garfield <la...@garfieldtech.com>: > On Sun, Apr 25, 2021, at 2:04 AM, Olle Härstedt wrote: >> > A total function is a function that is defined over the entire domain of >> > its >> > inputs. For example, addition is a total function over integers, >> > because >> > for every possible pair of integers you pass to it there is a logical >> > return >> > value. However, square root is not a total function over integers >> > because >> > there are some integers you pass it for which there is not >> > representable >> > return value. (Negative numbers, unless you get into imaginary numbers >> > which PHP doesn't support.) In those cases, you have to throw an >> > exception >> > or return an error code or similar. >> >> Maybe nitpicking, but PHP-land shouldn't make up their own >> definitions: "A total function is a function that is defined for all >> possible values of its input. That is, it terminates and returns a >> value." >> https://softwareengineering.stackexchange.com/questions/334874/in-the-context-of-functional-programming-what-are-total-functions-and-partia >> >> Which means a total function is guaranteed to not have any errors, >> like exceptions or division by zero. Compare with languages F* or Koka >> which support this notation. > > That... is literally what I said. There was no making up definitions. I > was using the actual mathematical definition. PHP is quite capable of > having total functions, they're a good thing, and we should try to encourage > them where feasible.
What's the point of encouraging total functions if you can't express the totality in the type system? Olle -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
